Abstract: A waterproof housing for a digital device includes a lens mount system having a threaded aperture provided on the housing, a lens arrangement including an optical lens coupled to a threaded collar, and a positioning assembly for fixedly locating the lens arrangement to the housing at a predetermined rotational engagement position of the threaded collar to the threaded aperture. The positioning assembly includes a releasable locking pin that is located in the housing adjacent to the threaded aperture, and a recess in a mounting surface of the lens arrangement for receiving a locking end of the pin when the lens arrangement and the housing are positioned at the predetermined engagement position. At this position, an optical feature of the lens arrangement is located at a predetermined desired distance from an optical plane of a camera of a digital device positioned within the housing.